夏季广东降水异常变化与夏季风

利用广东省３６个地面站降水量资料和ＮＣＥＰ８５０ｈＰａ再分析资料，采用相关分析和合成对比分析方法，探讨了广东降水变化与夏季季风活动的关系。发现广东夏季降水量变化与南海北部西南风大小成显著正相关，但并不能由此得出南海北部西南季风强广东降水多的结论。前汛期（４－６月），西南季风可以给广东带来降水，但降水的变化与西南季风强度变化关系不显著，５－６月份甚至出现热带西南季风弱广东降水反而强的情况，其主要的影响来自于副热带季风的加强。后汛期（７－９月），当西南季风在南海中北部地区加强，副热带季风对广东影响减弱时，广东降水增大。     

THE TIMING OF SOUTH-ASIAN HIGH ESTABLISHMENT AND ITS RELATION TO TROPICAL ASIAN SUMMER MONSOON AND PRECIPITATION OVER EAST-CENTRAL CHINA IN SUMMER

The timing of the South Asian High (SAH) establishment over the Indochina Peninsula (IP) from April to May and its relations to the setup of the subsequent tropical Asian summer monsoon and precipitation over eastern-central China in summer are investigated by using NCEP/NCAR daily reanalysis data, outgoing longwave radiation (OLR) data and the daily precipitation data from 753 weather stations in China. It is found that the transitions of the zonal wind vertical shear and convection establishment over tropical Asia are earlier (later) in the years of early (late) establishment of SAH. In the lower troposphere, anti-cyclonic (cyclonic) anomaly circulation dominates the equatorial Indian Ocean. Correspondingly, the tropical Asian summer monsoon establishes earlier (later). Furthermore, the atmospheric circulation and the water vapor transport in the years of advanced SAH establishment are significantly different from the delayed years in Asia in summer. Out-of-phase distribution of precipitation in eastern-central China will appear with a weak (strong) SAH and western Pacific subtropical high, strong (weak) ascending motion in the area south of Yangtze River but weak (strong) ascending motion in the area north of it, and cyclonic (anti-cyclonic) water vapor flux anomaly circulation from the eastern-central China to western Pacific. Accordingly, the timing of the SAH establishment at the upper levels of IP is indicative of the subsequent onset of the tropical Asian summer monsoon and the flood-drought pattern over eastern-central China in summer.     

东亚夏季风与中国夏季降水年际异常的分型研究

以海陆气压差定义的夏季风强度指数为依据,讨论了东亚夏季风年际异常与中国夏季降水的关系,发现东亚夏季风强时,中国夏季降水可能多也可能少,但以少雨为主,季风弱时,中国降水也是或多或少,但以多雨为主,依此可以将季风与降水的异常关系分成强季风强降水（Ａ）,强季风弱降水（Ｂ）,弱季风强降水（Ｃ）,弱季风弱降水（Ｄ）四种关系,其中（Ａ）型和（Ｄ）型,（Ｂ）型和（Ｃ）型的降水呈反相似性分布,主要特殊性反映在东北     

DIURNAL VARIATIONS OF SUMMER PRECIPITATION IN SHANGHAI

This paper investigates the diurnal variations of summer precipitation in Shanghai by using the city''s hourly precipitation data over a span of 35 years. The result shows that the precipitation peaks twice, in the morning and in the afternoon. Precipitation in the morning is characterized by light to moderate rain, and that in the afternoon by heavy to super heavy rain. The peak of short-duration precipitation is mostly found in the afternoon and at dusk, and that of long-duration precipitation in the morning. Most of the precipitation events in Shanghai are of a short duration of 2-3 hours. Basically, the precipitation is spatially distributed in three areas: the eastern coastal and central urban area, where the precipitation peaks mostly in the afternoon, the southern coastal area, where the precipitation peaks both in the afternoon and during the night, and the western area, where long-duration precipitation accounts for a much larger proportion than the other two areas.     

南亚夏季风爆发前后降水量时空变化特征

用南亚夏季风爆发前后的降水量资料作了经验正交函数分解（EOF）,分析表明,南亚夏季风的爆发主要体现在降水的突然增加和季风雨带的快速推进上,雨带的时空分布有突变的特点。第1模态反映了南亚夏季风爆发前后季风区降水量的突然增加。第2模态反映了南亚夏季风爆发前后季风降水从南向北的快速推进过程。第3模态反映了季风爆发期间南亚季风区降水量的东西分布型态,及在季风爆发后印度半岛降水快速增加的过程。第4模态反映了印度次大陆东海岸降水的准双周振荡型态。     

亚洲热带气候态夏季风涌传播特征及其对中国降水的影响

基于1979—2020年逐日的NOAA向外长波辐射资料、NCEP/NCAR再分析风场资料,以及全球CMAP再分析降水资料,探讨了气候态亚洲热带夏季风涌的传播过程及与我国夏季相应的降水联系。分析结果表明,主汛期亚洲热带气候态夏季风季节内振荡(CISO)活动是亚洲夏季风活动的主要特征,随时间北传的亚洲热带夏季风CISO称为亚洲热带夏季风涌,主要有南亚夏季风涌和南海夏季风涌。亚洲热带夏季风涌的传播可分为四个阶段。在亚洲热带夏季风涌的发展阶段,印度洋区域低频气旋与对流活跃,孟加拉湾和南海热带区域被低频东风控制,我国大部分地区无降水发生,降水中心位于两广地区。当进入亚洲热带夏季风涌活跃阶段,孟加拉湾和南海热带地区低频气旋和对流活跃,东亚低频“PJ”波列显著,我国降水中心北移到长江以南的附近区域。亚洲热带夏季风涌减弱阶段,孟加拉湾与南海低频气旋消亡,对流减弱,低频西风加强,日本南部附近为低频反气旋控制,我国长江中下游低频南风活跃,降水中心也北移到长江中下游地区,而华南地区已基本无降水,此阶段的大气低频环流场与亚洲热带夏季风涌发展阶段基本相反。进入亚洲热带夏季风涌间歇阶段时,孟加拉湾和南海热带地区低...     

夏季北大西洋涛动与我国天气气候的关系

利用1873-1995年北半球月平均海平面气压（SLP）资料，计算了夏季北大西洋涛动指数（NAOI）。通过NAOI与我国降水、气温和北半球球流5的相关计算以及强、弱小涛动年北半球环流异常的合成分析，发现，夏季强NAOI年，副高偏强，我国西南地区降水偏少，易出现一类和二类雨型；我国大部分地区气温明显偏高，此外，还研究了多时间尺度上，NAOI与东亚夏季风的关系，结果表明，夏季NAOI与东亚夏季风在年际、年代际、基本态尺度上都存在显著相关，强NAOI年，对应是强东亚夏季风特征，当NAOI处高（低）基本态时，夏季风处于高（低）基本态。     

东亚副热带夏季风环流指数及其与中国气候的关系

采用大气环流正、斜压分解方法,从东亚副热带夏季风为正、斜压混合型季风观点出发,定义并计算了1958-1997年东亚副热带夏季风环流指数。该环流指数与1961-1995年中国160站夏季降水、气温的相关分析表明,它与中国东部夏季降水和气温的关系密切：强季风年,以河套地区为中心的黄河流域及华北地区多雨,长江流域少雨,华南和东南沿海多雨,以长江流域为中心的全国绝大部分地区气温偏高。弱季风年情况相反。此外,还将该环流指数与目前常用的4种东亚夏季风指数进行了对比分析。     

ENSO对亚洲夏季风环流和中国夏季降水影响的诊断研究

文中以ＳＶＤ分析技术为基础,发展了一种用以提取一个矢量场和一个标量场耦合信号的统计诊断方法——联合ＳＶＤ方法（简记为ＣＳＶＤ）,并运用ＣＳＶＤ分析了ＥＮＳＯ对亚洲季风环流系统及中国夏季降水的年际变化的影响。结果表明,在ＥｌＮｉｎｏ年,印度夏季风减弱,东亚夏季风增强;而在ＬａＮｉｎａ年,印度夏季风增强,东亚夏季风减弱。且ＥＮＳＯ对亚洲夏季风环流影响显著的区域主要在长江流域南北气流交汇区和索马里急流区,而对中国夏季降水影响最显著的区域则在江淮流域。     

THE EAST ASIAN SUBTROPICAL SUMMER MONSOON INDEX AND ITS RELATION WITH THE CLIMATE ANOMALIES IN CHINA

A new East Asian subtropical summer monsoon circulation index is defined, where the barotropic and baroclinic components of circulation are included. Results show that this index can well indicate the interannual variability of summer precipitation and temperature anomalies in China. A strong monsoon is characterized by more rainfall in the Yellow River basin and northern China, less rainfall in the Yangtze River basin, and more rainfall in south and southeast China, in association with higher temperature in most areas of China. Furthermore, comparison is made between the index proposed in this paper and other monsoon indexes in representing climate anomalies in China.     

亚洲季风年代际振荡及与天文因子的相关

主要通过滑动ｔ－检验方法和相关统计,分析了近５０年来南亚季风、东亚季风以及高原季风的相互关系,并对其与太阳黑子周期长度（ＳＣＬ）和地球自转速度（Δω）的关系进行了讨论。结果表明：三种亚洲季风虽然在年际变化上相关不好,但在年代变化上具有很好一致性;亚洲季风的年代际变化与ＳＣＬ和Δω均相关很好,其中以与Δω关系最好,且Δω的变化超前亚洲季风的变化。对日地因子的短期变化如何影响亚洲季风年代际振荡提出了初     

EFFECTS OF ANOMALOUS HEATING ON SUMMER MONSOON OVER ASIA

Based on a zonally non-uniform mean circulation in summer simulated by numerical modelling,perturba-tion heatings ever South Asia and a perturbation cooling over Northwest Australia were incorporated in a nu-merical model to discuss their effects on summer monsoon over Asia and the structure of flow disturbance.     

南海夏季风强度与我国汛期降水的关系

对4种南海夏季风强度指数(1951～1998年)进行了对比分析,发现尽管它们在某些年份有差异,但在年际变化总体趋势上仍表现一致,并且由它们所确定的季风强弱年也基本相同.统计分析了南海夏季风强度与我国汛期降水的关系,结果表明,南海夏季风强(弱)年,我国夏季雨带型呈Ⅰ(Ⅲ)类分布,长江中下游地区夏季(6～7月)少雨干旱(多雨洪涝),广东省后汛期降水以偏涝(正常和偏旱)为主.南海夏季风强度指数与夏季长江中下游区降水和淮河区降水有显著的反相关,与江南区降水和华南后汛期降水有显著的正相关.我国夏季出现的严重洪涝(如1998年长江流域特大洪涝和1994年华南特大暴雨)与南海夏季风的强度异常有关.此外,分析还表明,南海夏季风活动强弱造成的北半球东亚500 hPa位势高度场的经向波列型遥相关是影响中国夏季降水的一个重要机制.     

利用空间均匀网格对中国夏季降水异常区域特性的初步分析

用方差极大正交转动ＥＯＦ（Ｖａｒｉｍａｘ　ＥＯＦ）及点相关图法分析了夏季总降水（６、７、８月降水之和）及逐月降水的区域特性。使用的资料为全国范围４７个５°×５°经纬度网格上的降水资料，分析时段为１９５９—１９９４年。分析结果表明，由于采用了空间均匀的格同资料，本分析除进一步证实了中国东部地区降水异常的区域特性外，也揭示了西部地区降水异常的区域特性及沿长江流域东西方向上降水异常的相互关系。夏季总降水异常最显著的区域特性是江淮流域与河套及华南反相关。另外沿长江流域，四川盆地的降水异常与青藏高原东部及江淮流域的降水异常也存在着反相关联系。西部地区的区域特性为青藏高原中东部南北两侧为负相关，并且青藏高原中东部南侧的降水异常与华北东部及东北南部为正相关。上述的空间模都有准２—３ａ及１０ａ左右的周期。逐月降水的分析表明，６月份，江淮流域、华北东部及东北大部分地区为正相关。７月，河套地区与江淮流域的降水异常呈现一定的负相关联系，８月份降水异常的区域特性与夏季总降水异常的区域特性极其一致。     

1998年夏季中国南部低频降水特征与南海低频夏季风活动

1998年 5～ 8月 4 0°N以南的中国地区低频 (含准 4 5天、准 2 3天和准14天 )降水率及其方差占总降水率及其方差的比重很大 ,因此研究低频降水及与其相对应的低频环流对长江流域洪涝的影响是很重要的。研究表明 ,准 4 5天东西向低频槽脊由南海不断向北传播 ,以及低槽中的低频低涡向西传播是形成长江流域低频降水的重要原因 ,低频降水主要位于低频西风区 ,而低频槽南侧的低频西风实质是南海低频夏季风的表现 ,由此可见 ,南海低频夏季风的向北传播对长江流域降水具有重要贡献。     

夏季北半球500hPa月平均场遥相关型及其与我国季风降水异常的关系

用一点相关法计算了盛夏北半球５００ｈＰａ遥相关型，得到７月份北半球存在７个遥相关型，８月份有６个遥相关型。研究了它们的中心，计算了各遥相关型的历年强度指数（１９５１－１９９０），研究了它们的年际变化、月际变化。指出７月份的东亚太平洋型、北美东西遥相关型；８月份的ＥＡＰ型、欧亚型与我国盛夏季风降水关系密切。１９９１年夏季发生的弱ＥＡＰ型是江淮流域大涝的一个重要原因。     

1991年北半球夏季风及江淮流域降雨量的低频振荡

根据１９９１年５－８月江淮特大暴雨资料，使用功率谱和带通滤波结合的方法，研究了１９９１年夏季风和江淮梅雨的准周期振荡，探索季风对异常梅雨的影响。分析指出，１９９１年北半球夏季风活动，江淮流域湿度场和降雨量变化均存在显著的准２４天周期振荡，夏季风的周期振荡，主要表现在西南季风（东南季风不明显），它的位相比降雨量提前２－４左右，其振幅大小较好地反映了降雨量的大小。     

SEASONAL VARIATIONS OF NET RADIATIVE HEATING IN THE EARTH-ATMOSPHERIC SYSTEM AND ITS RELATIONS TO ASIAN SUMMER MONSOON

Satellite-derived data of the outgoing longwave radiation(OLR), net shortwave radiation at the tropopause(SRT)and circulation information as predicted by NCEP are used in the work to study seasonal variations of net radiative heating in the earth-atmospheric system and its relationship with the Asian summer monsoon. As is shown in the result, the zonal deviations of the zonal deviations of the heating, manifested as mutations in direction between land and sea with seasons, is an indication of the thermal difference between them. Being a month earlier than that in the general circulation from spring to summer, the seasonal reversal of directionmay be playing an essential role in triggering the onset and withdrawal of summer monsoon in Asia.     

A STUDY ON RESPONSE OF PRECIPITATION IN CHINA TO MONSOON INTRASEASONAL OSCILLATION

Temporal and spatial evolution characteristics of the 30-60 day oscillation (intraseasonal oscillation, ISO) of summer rainfall in China and the effects of East Asian monsoon on the rainfall ISO are analyzed in this paper. Results show that the annual and decadal variations of the oscillation exist between 1960 and 2008, and the intensity is weakest in the late 1970s and early 1980s. In the typical strong years of the rainfall ISO obtained from empirical orthogonal functions (EOF mode 1), an anticyclone is in northwestern Pacific and a cyclone is in the east of China. In the typical weak years, the wind ISO is much weaker. The low-frequency zonal wind and water vapor transport from the low latitudes to mid-latitudes in the typical strong years, and the oscillation strength of diabatic heating is much stronger than that in the weak years of the rainfall ISO. The anomaly characteristics of the rainfall ISO show anti-phases between the Yangtze River basin and south of China. As for the typical strong years of the rainfall ISO in the Yangtze River basin (EOF mode 2), the main oscillation center of water vapor is in the east of China (20-30°N, 110-130°E). In the peak (break) phase of the rainfall oscillation, a low-frequency cyclone (anticyclone) is in the Yangtze River basin and an anticyclone (cyclone) is near Taiwan Island. In addition, the peak rainfall corresponds to the heat source in the Yangtze River basin and the heat sink in the Qinghai-Tibet Plateau. As for the typical strong years of the rainfall ISO in the south of China, the main oscillation center of water vapor is south of 20°N. In the peak (break) phase of the rainfall ISO, a low-frequency cyclone (anticyclone) is in the south of China and an anticyclone (cyclone) is in the Philippines. The peak rainfall corresponds to the heat source in the south of China and the South China Sea, and the heat sink in the west of Indochina.     

青藏高原春季积雪异常对亚洲季风降水影响的数值试验

该文利用一个移植和改进的ＣＯＬＡＡＧＣＭ谱模式，进行了青藏高原春季积雪异常对亚洲夏季风环流和降水影响的数值试验。试验结果指出：高原地区３月份积雪增多，亚洲地区６，７月的夏季风环流明显减弱，降水减少。